Electronic fuel injection systems for automotive engines normally provide actuating pulses for operating solenoid-type fuel injectors. These pulses are variable as to width in response to many engine operating conditions including rotational speed, intake manifold vacuum, throttle angle, etc. Engine idle speeds are frequently set by means of a simple set screw adjustment which may include a temperature-responsive means for permitting somewhat faster idle speeds when the engine is cold. Such simple adjustment means are not always capable of compensating for a number of engine operating variables including the reduction in friction within the engine as it is run in. Normally an idle speed adjustment will be made at the factory, at least one other adjustment made at the dealership at the time the car is sold, and still another after the engine has been run for about 150 miles. With this and various other loading factors such as that imposed by air conditioning which may or may not be turned on, with large operating temperature variations and other variables, it becomes apparent that providing some type of closed loop speed control on idle speed is desirable. Such system must be capable of maintaining control system stability over a wide range of engine operating conditions. One standard means of increasing stability is to reduce the gain of the system; however, applicants have found that a very low gain will permit a substantial change in idle speed set point as engine conditions are changed. Thus a stable idle speed reference is highly desirable to avoid such changes in set point. Good stability should be assured despite changes in coolant temperature, air conditioning load, rapid fluctuations between idle flow conditions, and part throttle conditions, etc.